Oxaprozin (4,5-diphenyl-2-oxazolepropanoic acid) is a nonsteroidal antiinflammatory agent which also possesses antipyretic, uricosuric and immunologic properties. It is believed, like other nonsteroidal antiinflammatory agents of the propionic acid type, that oxaprozin functions as a prostaglandin biosynthesis inhibitor.
The metabolism of oxaprozin (U.S. Pat. No. 3,578,671) was studied by Janssen et al., Drug Metabolism and Disposition, 6 (No. 4), 465 (1978), who found two major metabolites which were denominated metabolites II and III. Metabolite III was identified as 4-(4-hydroxyphenyl)-5-phenyl-2-oxazolepropanoic acid by preparation of its 4-methoxyphenyl ether and comparison with a known sample of 4-(4-methoxyphenyl)-5-phenyl-2-oxazolepropanoic acid prepared in U.S. Pat. No. 3,578,671. The structure of metabolite II was not further elucidated than to identify the presence of an aromatic hydroxy group.